How to back up your media in iTunes
Mark is right when it pertains to installed applications. Some portable applications, or those that are merely unzipped and keep data in the AppData folder can be totally backed up by copying a couple of folders. One example is Chromium browser snap shot. Not the mini installer but the win 32 zip.
Also I write a bunch of little hotkey tray utilities. Nearly all can be backed up just by copying the containing folder you unzipped into.
But it if uses the Registry, dlls etc.. you're better off imaging your system partition and any with installed programs.